1. Field of the Invention
The present invention relates to an automatically opening and closing large-sized and heavy pivotable lid for a receptacle structure, such as a container for high-temperature and high-pressure treatment or a vault, and more particularly to a safety device for stopping the pivotal movement of the lid in the presence of any obstacle, such as a person or an object, within the range of movement of the lid, to prevent any accident.
2. Description of the Prior Art
In presure containers for dyeing textile products under high temperature and pressure and for treating inorganic or metallic products with high-temperature vapor or in vaults, because of its largeness and heaviness, the lid is opened and closed automatically, not manually, from a view point of efficiency and safety. Especially in the case where there are installed a number of such containers and the treatment processes therein are remotely and collectively controlled, the opening and closing of the individual lid is also automatically controlled.
In order to prevent any accident during the opening and closing of such automatic lid, there have been proposed a variety of safety means: a warning sign in eye-catching color on the lid or the floor, a guard fence, and a warning signal in sound or light.
However, any of these known safety means must rely on the carefulness of a person and hence is not sufficient. Further, the known safety means cannot cope with the condition if a thing or materials are left within the area of movement of the lid.